For improving the surface of a plastic lens which has become frequently used in recent years, a sol of metal oxides having high refractive index is used as a component of a hard coating agent applied to this surface.
Proposed is a stable sol containing modified metal oxide colloids having a particle diameter of 4.5 to 60 nm which is formed by coating the surface of colloidal particles of metal oxides having a valence of 3, 4 or 5 which has a particle diameter of 4 to 50 nm as a core with tungsten oxide-tin oxide composite colloidal particles having a particle diameter of 2 to 7 nm in which the mass ratio of WO3/SnO2 is 0.5 to 100, in which the content of all of these metal oxides is 2 to 50% by mass (for example, see Patent Document 1).
Proposed is a stable sol of a modified SnO2—ZrO2 composite containing particles having a structure in which the surface of SnO2—ZrO2 composite colloidal particles having a mass ratio of ZrO2/SnO2 of 0.02 to 1.0 and a particle diameter of 4 to 50 nm as a core are coated with WO3—SnO2 composite colloidal particles having a mass ratio of WO3/SnO2 of 0.5 to 100 and a particle diameter of 2 to 7 nm (for example, see Patent Document 2).
Proposed is a stable sol containing: a structure in which colloidal particles of tin oxide and colloidal particles of zirconium oxide are bonded to each other in a ratio of ZrO2/SnO2 of 0.02 to 1.0 based on the mass of these oxides; and modified tin oxide-zirconium oxide composite colloidal particles having a particle diameter of 4.5 to 60 nm which is formed by coating the surface of tin oxide-zirconium oxide composite colloidal particles having a particle diameter of 4 to 50 nm as a core with tungsten oxide-tin oxide-silicon dioxide composite colloidal particles having a WO3/SnO2 mass ratio of 0.1 to 100, a SiO2/SnO2 mass ratio of 0.1 to 100 and a particle diameter of 2 to 7 nm, in which the content of all of these metal oxides is 2 to 50% by mass (for example, see Patent Document 3).
Proposed is a stable sol containing: a structure in which colloidal particles of tin oxide obtained by a reaction between metal tin, an organic acid and hydrogen peroxide and colloidal particles of zirconium oxide are bonded to each other in a ratio of ZrO2/SnO2 of 0.02 to 1.0 based on the mass of these oxides; and modified tin oxide-zirconium oxide composite colloidal particles having a particle diameter of 4.5 to 60 nm which is formed by coating the surface of tin oxide-zirconium oxide composite colloidal particles having a particle diameter of 4 to 50 nm as a core with tungsten oxide-tin oxide-silicon dioxide composite colloidal particles having a WO3/SnO2 mass ratio of 0.1 to 100, a SiO2/SnO2 mass ratio of 0.1 to 100 and a particle diameter of 2 to 7 nm, in which the content of all of these metal oxides is 2 to 60% by mass (for example, see Patent Document 4).
Proposed is a production method of a metal oxide sol, characterized in that the method includes: a step for heating a metal compound in an aqueous medium containing a carbonate salt of quaternary ammonium at 60 to 110° C.; and a step for performing a hydrothermal processing at 110 to 250° C. (For example, see Patent Document 5).    [Patent Document 1]
Japanese Patent Application Publication No. JP-A-3-217230 (claims)    [Patent Document 2]
Japanese Patent Application Publication No. JP-A-6-24746 (claims)    [Patent Document 3]
Japanese Patent Application Publication No. JP-A-2000-281344 (claims)    [Patent Document 4]
Japanese Patent Application Publication No. JP-A-2005-296940 (claims)    [Patent Document 5]
WO 06/019004 Pamphlet